The term "phase change material" as used herein shall be read to mean; "a substance which has the property of remaining at substantially a constant temperature while receiving or giving up significant amounts of heat energy at a temperature at which the material undergoes a change of state". For example; water changes state between liquid and solid at 32 degrees Fahrenheit (0 degrees Celsius). Water will remain at 32 degrees Fahrenheit until the change of state is complete and approximately 144 BTU/pound of water is absorbed or yielded up during the change of state.
The term "thermostat" used herein shall be read to mean "a control means which responds to temperature to initiate, maintain or change the operating mode of a device".
Panels which collect solar energy are well known in the art. State of the art panels often suffer from a number of deficiencies.
One such deficiency of many such panels is the need to provide large often expensive heat storage means and often elaborate and less than satisfactory mechanisms for transferring heat from the panel to storage and from the storage means to the space to be heated.
Another deficiency of state of the art panels is the need for reliable and efficient temperature control both for the panel and for the space to be heated.
Yet another deficiency of many such panels is that of installation and maintenance cost and convenience. Experience has shown that such panels are subjected to a range of mechanical damage from abnormal weather and environmental conditions and activities in the vicinity of the panels. Therefore, provision must be made for the maintenance and repair of even the most well constructed and durable of so called maintenance free panels.
Yet another deficiency of many such panels is that of efficiency. Undesirable heat losses and/or gains often diminish the efficiency of such panels to the point they are not cost effective.